Inner space of a package for an electronic component (hereinafter referred to as electronic component package) such as a piezoelectric resonator device is hermetically sealed so as to prevent electrode characteristics of an electronic component element mounted in the inner space from deteriorating.
The electronic component packages of this kind include one constituted of two sealing members, namely a base and a lid, having a housing formed into a rectangular parallelepiped package. In the inner space of such a package, an electronic component element such as a piezoelectric resonator plate is bonded to and held by the base. The electrodes of the electronic component element in the inner space of the package are hermetically sealed by the base with the lid being bonded with each other.
For example, in a piezoelectric resonator device (corresponding to an electronic component in the present invention) disclosed in Patent Literature 1, a piezoelectric resonator plate is hermetically sealed in inner space of a package constituted of a base and a lid bonded with each other by brazing filler metal. In such a piezoelectric resonator device, a laminated body obtained by laminating, for example, an Mo layer, an Ni layer, and an Au layer in order is provided in an outer circumference portion of one main surface of the base before being bonded with the lid. Meanwhile, in an outer circumference portion of one main surface of the lid, brazing filler metal containing AuSn alloy is provided before the lid is bonded with the base. By performing heat treatment in a state where the laminated body provided on the base and the brazing filler metal provided on the lid are superimposed on each other, the laminated body and the brazing filler metal melt to form a bonding material, and thus the base and the lid are bonded with each other.
Incidentally, gas is produced when brazing filler metal is heated and melted. If the gas produced here enters the inner space of the package of the piezoelectric resonator device, the entering gas affects vibration characteristics of the piezoelectric resonator plate. Specifically, A CI value (equivalent series resistance) deteriorates, or fluctuation of a frequency in aging characteristics occurs.
In the piezoelectric resonator device disclosed in Patent Literature 1 mentioned above, the outer circumference portion of the lid provided with the brazing filler metal is formed in parallel with the outer circumference portion of the base provided with the laminated body, resulting in a configuration in which the heated molten material of the brazing filler metal is likely to flow in a surface direction of the main surface of the lid toward the inside of the piezoelectric resonator package. As a result, a problem arises in that a large amount of the gas produced due to the heated and melted brazing filler metal enters the inner space of the package of the piezoelectric resonator device and causes the vibration characteristics of the piezoelectric resonator plate to deteriorate.